code: def df_ddf():
      import numpy as np
  
      df = pd.DataFrame(
          {
              "str_col": ["abc", "bcd", "cdef", "DEFG"],
              "int_col": [1, 2, 3, 4],
              "dt_col": np.array(
                  [int(1e9), int(1.1e9), int(1.2e9), None],
                  dtype="M8[ns]",
              ),
          },
          index=["E", "f", "g", "h"],
      )
  
      df["string_col"] = df["str_col"].astype("string")
      df.loc["E", "string_col"] = pd.NA
  
      ddf = dd.from_pandas(df, 2)
  
      return df, ddf
  
imports: from __future__ import annotations
  import contextlib
  import numpy
  import pytest
  import dask.dataframe
  from dask.dataframe._compat import PANDAS_GE_140, PANDAS_GE_210
  from dask.dataframe._pyarrow import to_pyarrow_string
  from dask.dataframe.utils import assert_eq, pyarrow_strings_enabled
label_desc: Use image node_id 4 for calling a global function with example usage: df_ddf() and returns: df,  ddf